Obese Drivers Face Higher Risks in Cars

Sep 29 , 2020

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Obese Drivers Face Higher Risks in Cars

The medical community continues to sound the alarm about obesity, with the American Medical Association declaring it a disease. Nearly 36 percent of Americans age 20 or older are considered obese, according to the federal Centers for Disease Control and Prevention. And while some health experts argue against the disease label, the reality is that being obese puts people at an increased risk for developing diabetes, heart disease and several types of cancer.

The health risks don't end there. Several recent studies found that obese people are not as safe behind the wheel. One culprit may be ill-fitting seatbelts, or the failure to use a seatbelt at all.

Obesity is defined as having a body mass index (BMI) over 30. A healthy BMI is between 18.5 and 25. Morbidly obese individuals, defined as those with a BMI of more than 40, are 56 percent more likely to die in a car crash than normal-weight individuals. That conclusion comes from a 2010 State University of New York at Buffalo analysis of national Fatality Analysis Reporting System (FARS) data of more than 155,000 drivers involved in severe motor vehicle accidents.

Those who were moderately obese, with a BMI between 35 and 40, were 21 percent more likely to die in a car crash.

A 2012 study by transportation safety researchers at the University of California at Berkeley and the University of West Virginia had more startling results: Drivers with a BMI between 30 and 34.9 had an increased risk of death of 21 percent. For those with a BMI between 35 and 39.9, the risk was 51 percent greater. Those with a BMI of 40 and over had an 80 percent increased risk of death.

The Problem With Buckling Up

The seatbelt is another life saver in vehicular accidents, keeping occupants from being thrust forward or thrown out of a vehicle. Proper seatbelt use is the "single most important thing" drivers and passengers can do to lessen the risk of injury in a crash, Rader says.

But obese drivers often have difficulty with seatbelts, either wearing them the wrong way or not at all.

Here's one area where those slimmer crash test dummies make a difference. "Seatbelts are designed and tested on dummies to fit very snug, not loose," says Reed, director of UMTRI's Human Motion Simulation Laboratory.

A seatbelt works best when the belt rests close to the bone in your shoulder and in your pelvis, tight across the collarbone and low across the hip. In research using human modeling software, Reed has shown that obesity has a negative effect on seatbelt fit.

"In people who are carrying a lot of excess tissue, the belt is pushed forward and essentially it's slack," Reed explains. "So in a crash, especially a frontal crash, the vehicle stops and the person keeps sliding forward until the belt arrests."

"In an obese person, it has to push aside all of that soft tissue in order to get down to the bone where it can really start to slow a person down," he says.

A recent University at Buffalo study found obese drivers are less likely than normal weight drivers to use their seatbelts. Researchers analyzed FARS data of nearly 337,000 drivers involved in severe crashes where a death occurred. The more the person weighed, the less likely they were to wear their seatbelts, says Jehle, the study's lead author. Normal weight drivers were 67 percent more likely to wear seatbelts than drivers who were morbidly obese.

"The results weren't all that shocking," says Jehle. "For morbidly obese people, it's harder to put a seatbelt on properly, and harder to find ones that fit."

Morbidly obese people aren't just a marginal few individuals. More than 6 percent of American adults are morbidly obese, a rate that has risen rapidly in recent years, according to a 2012 study of data from the Behavioral Risk Factor Surveillance System.

This product is for those who otherwise can't buckle up.


  • The extender belt is designed to provide safety when the original vehicle belt is not long enough. It's ideal for use for fat people, pregnant women, firefighters, and service personnel equipped with heavy equipment belt.


To stay safe behind the wheel, no matter your size, do the following:

Always wear a seatbelt and make sure your passengers do, too.
Make sure your seatbelt fits tight across your shoulder and low and tight across your lap. If you have significant girth around your waist, place the lap portion of the belt underneath the soft tissue, not over it, says Matthew Reed, head of UMTRI's biosciences group. The same goes for pregnant women.
If you need a seatbelt extender, first ask the vehicle manufacturer if they offer these. If they don't, ask which extenders are compatible with your vehicle's make and model.
"Seatbelt extenders are a good option for people who can't comfortably use regular seatbelts," says Russ Rader, spokesperson for the IIHS. However, NHTSA hasn't tested seatbelt extenders for safety and several car manufacturers do not offer them, citing the lack of testing on their efficacy in a crash.